Electrolyte for Lithium Cell

ABSTRACT

An electrolyte, an electrolyte solvent, and an electrolyte additive, in particular for a lithium cell, include at least one ether. The at least one ether has at least one of the general chemical formula: R11R12R13C—(CR14R15)x1-[O—(CR31R32)a-(CR33R34)b]c-O—(CR24R25)x2-CR21R22R23 and of the general chemical formula: R41R42R43C—(CR44R45)y1-O—(CR54R55)y2-CR51R52R53.

The present invention relates to an electrolyte, to an electrolytesolvent, to an electrolyte additive, to ethers and to the use thereof.

STATE OF THE ART

Lithium ion cells have a positive electrode (cathode), a negativeelectrode (anode) and a porous separator disposed in between. Thepositive and negative electrodes each comprise a material into whichlithium ions (Li⁺) can be intercalated and out of which they can bedeintercalated again, reversibly. The intercalation and deintercalationfor lithium ions takes place in the presence of an electrolytecomprising a conductive lithium salt and at least one electrolytesolvent.

In most lithium ion cells both in the consumer sector, for example incell phones, MP3 players or power tools, and in the automotive sector,for example in electrical vehicles and hybrid vehicles, the conductivelithium salt used is lithium hexafluorophosphate (LiPF₆). In order todissolve the conductive lithium salt, ethylene carbonate (EC) is presentin virtually all electrolytes currently used for lithium ion cells. Theseparator used is usually a polyethylene or polypropylene separator.

DISCLOSURE OF THE INVENTION

The present invention relates to an electrolyte, to an electrolytesolvent and to an electrolyte additive, especially for a lithium cell,for example a lithium ion cell, comprising at least one ether, and tocorresponding ethers and to the use thereof, more particularly, the atleast one ether may be a symmetric or asymmetric ether, for example a(mono)ether or (oligo)ether.

A lithium cell may especially be understood to mean a cell having anelectrochemical reaction based on an electrochemical reaction oflithium. A lithium cell may either be a lithium ion cell having alithium intercalation anode, for example made from graphite, or alithium metal cell having an anode made from metallic lithium or alithium alloy.

It has been found that symmetric and asymmetric ethers, especiallysymmetric or asymmetric (mono)ethers or (oligo)ethers, firstly have adielectric constant which may be higher than the dielectric constant ofacyclic carbonates such as dimethyl carbonate (DMC), ethyl methylcarbonate (EMC) or diethyl carbonate (DEC). For example, symmetric andasymmetric ethers, especially symmetric or asymmetric (mono)ethers or(oligo)ethers, may have a dielectric constant of not less than 7,whereas the dielectric constant of acyclic carbonates, dimethylcarbonate (DMC), ethyl methyl carbonate (EMC) or diethyl carbonate (DEC)is typically only about 2 to 3. On the other hand, symmetric andasymmetric ethers, especially symmetric or asymmetric (mono)ethers or(oligo)ethers, may have a much lower viscosity than cyclic carbonatessuch as ethylene carbonate (EC) and propylene carbonate (PC). Forexample, symmetric and asymmetric ethers, especially symmetric orasymmetric (mono)ethers or (oligo)ethers, even at room temperature mayhave a viscosity of about 0.3 to 0.6 mPa*s, whereas the viscosity ofethylene carbonate (EC) at 40° C. is 1.9 mPa*s.

This advantageously enables in an electrolyte containing cyclic and/oracyclic carbonates, for example an ethylene carbonate-containingelectrolyte, through the use of one or more symmetric and/or asymmetricethers, a reduction in the proportion of cyclic and/or acycliccarbonates, especially the proportion of ethylene carbonate, and henceprovision of an electrolyte having a reduced viscosity and havingsimilarly good lithium ion solvation and coordination properties to anether-free electrolyte having a higher proportion of cyclic carbonates,especially having a high ethylene carbonate content.

Through the reduction in the proportion of cyclic carbonates, especiallyin the ethylene carbonate content, it is additionally possible in anadvantageous manner to reduce the interfacial tension of the electrolyteand hence to improve or accelerate the wetting propensity of theelectrolyte with respect to polyolefin separators such as polyethylene(PE) and/or polypropylene (PP) separators. This is advantageousespecially in the production of comparatively large lithium (ion) cells,since the electrolyte filling therein is a process step which generallytakes a long time in the case of conventional electrolytes having a highethylene carbonate content. The reason for this is that conventionalelectrolytes having a high ethylene carbonate content have a highsurface tension of about 44 dynes/cm, and therefore these polyolefinseparators, which typically have a surface tension of about 29-35dynes/cm, are wetted only slowly. The use of the ether-containingelectrolyte can advantageously bring about faster wetting of theseparator with the electrolyte, and, as a result, faster incorporabilityof the electrolyte into the lithium ion cell being produced, and henceadvantageous acceleration of the otherwise time-consuming process stepof electrolyte filling. In addition, a reduction in the proportion ofpropylene carbonate or a propylene carbonate-free configuration of theelectrolyte in the case of a graphite-containing anode can reduce orprevent exfoliation of the graphite by polycarbonate.

A reduction in the proportion of acyclic carbonates has the advantagethat acyclic carbonates having a generally low flash point can bereplaced by ethers having a higher flash point and hence the safety ofthe electrolyte can be improved.

However, addition of ethers while maintaining a high proportion ofcyclic and/or acyclic carbonates can also bring advantages, since theether can increase the solubility of the conductive salt or lithium saltin the electrolyte, and the electrolyte conductivity can advantageouslybe improved by a higher amount of conductive salt or lithium saltdissolved in the electrolyte.

In addition to use of ethers as cosolvent or solvent, surprisingly, eventhe addition of very small amounts of ether, for example in the rangefrom ≧0.5% by weight to ≦2% by weight, to the electrolyte, i.e. even theuse of ethers in the region of a conventional additive concentration,has been found to be advantageous since this can lead to improvedformation of what is called the SEI (“solid electrolyte interface”).

In order to achieve one or more of the above-described advantages, theat least one ether, especially symmetric or asymmetric ether, can beused in the context of the invention both as cosolvent and as additive,or else optionally as main solvent. The electrolyte, the electrolytesolvent and/or the electrolyte additive may optionally be ether-based.In this context, “main solvent” and “ether-based” may especially beunderstood to mean that the proportion of ethers, based on the totalamount of carbonates and ethers or based on the total amount of solvent,amounts to at least 50% by weight. Optionally, the electrolyte, theelectrolyte solvent and/or the electrolyte additive may becarbonate-free.

The invention provides an electrolyte comprising at least one cycliccarbonate and/or at least one acyclic carbonate and at least one ether.

In the context of one embodiment, the electrolyte comprises, based onthe total weight of the carbonates and ethers, for example based on thetotal weight of solvent, ≧0.1% by weight to ≦20% by weight of ethers.

For example, the at least one ether may be used as cosolvent(s), inwhich case the electrolyte, based on the total weight of the carbonatesand ethers, for example based on the total weight of solvent, maycomprise >2% by weight to ≦20% by weight, especially ≧5% by weight to≦10% by weight, of ethers.

Alternatively or additionally, however, at least one ether may also beused as additive.

In the context of a further embodiment, therefore, the electrolyte,based on the total weight of the carbonates and ethers, for examplebased on the total weight of solvent, comprises 0.5% by weight to 2% byweight of ethers.

Based on the total weight of the carbonates and ethers, for examplebased on the total weight of solvent, the electrolyte may comprise, forexample, ≧15% by weight to ≦40% by weight, especially ≧20% by weight to≦35% by weight, for example ≧25% by weight to ≦30% by weight, of cycliccarbonates and/or ≧50% by weight to ≦80% by weight, especially ≧55% byweight to ≦75% by weight, for example ≧61% by weight to ≦70% by weight,of acyclic carbonates.

An electrolyte which—based on the total weight of the carbonates andethers, for example based on the total weight of solvent—comprises ≧15%by weight to ≦40% by weight, especially ≧20% by weight to ≦35% byweight, for example ≧25% by weight to ≦30% by weight, of cycliccarbonates, ≧50% by weight to ≦80% by weight, especially ≧55% by weightto ≦75% by weight, for example ≧60% by weight to ≦70% by weight, ofacyclic carbonates and ≧0.1% by weight to ≦20% by weight, especially ≧5%by weight to ≦10% by weight and/or ≧0.5% by weight to ≦2% by weight, ofethers has been found to be particularly advantageous in terms of thelithium ion solvation or coordination properties, viscosity and wetting.For example, it has been found to be advantageous when the electrolyte,based on the total weight of the carbonates and ethers, for examplebased on the total weight of solvent, comprises about 25% by weight ofcyclic carbonates, for example ethylene carbonate (EC), about 70% byweight of acyclic carbonates and about 5% by weight of ethers, or about25% by weight of cyclic carbonates, for example ethylene carbonate (EC),about 65% by weight of acyclic carbonates and about 10% by weight ofethers, or about 30% by weight of cyclic carbonates, for exampleethylene carbonate (EC), about 60% by weight of acyclic carbonates andabout 10% by weight of ethers.

In the context of a further embodiment, the electrolyte furthercomprises at least one conductive lithium salt.

More particularly, the electrolyte may comprise lithiumhexafluorophosphate (LiPF₆).

In the context of a further embodiment, the at least one ether isselected from the group of the (mono)ethers, especially symmetric and/orasymmetric (mono)ethers, the (oligo)ethers, especially symmetric and/orasymmetric (oligo)ethers, and mixtures thereof. An oligoether mayespecially be understood to mean any ether having at least two to twentyether oxygen atoms. For example, an oligoether may have a repeat etherunit repeating, for example, 2 to 10 times.

In the context of a specific embodiment, the electrolyte comprises atleast one (mono)ether, especially symmetric and/or asymmetric(mono)ether, and/or at least one (oligo)ether, especially symmetricand/or asymmetric (oligo)ether, comprising at least one carboxylic acidgroup and/or carboxylic ester group and/or hydroxyl group and/or thiolgroup and/or halogen atom, especially fluorine atom, and/or stericallydemanding group. More particularly, the (mono)ether or (oligo)ether mayhave at least two groups of this kind, in which case the groups mayeither be different from one another or the same.

A sterically demanding group may especially be understood to mean agroup having a tertiary, quaternary, alkenylic (C—C double bond) oraromatic carbon atom, for example a branched or cyclic alkyl group oralkenyl group or an aryl group or a heteroaryl group.

More particularly, the (mono)ether or (oligo)ether may have at least twoidentical groups from those mentioned above. For example, the(mono)ether or (oligo)ether may have at least two carboxylic acid groupsand/or at least two carboxylic ester groups and/or at least two hydroxylgroups and/or at least two thiol groups and/or at least two halogenatoms, especially fluorine atoms, and/or at least two stericallydemanding groups.

Polar groups such as carboxylic acid groups, carboxylic ester groups,hydroxyl groups, thiol groups and halogen atoms, for example —CO₂M, —F,—Cl, —OH, —SH, can advantageously increase the polarity of the ether andhence improve the lithium solvation or coordination propensity thereof.For instance, it is advantageously possible to reduce the proportion ofcyclic carbonates or increase the electrolyte conductivity.

Sterically demanding groups, for example tert-butyl, can advantageouslyreduce the viscosity of the ether. For instance, the wetting canadvantageously be improved and/or the electrolyte filling operationaccelerated.

In the context of a specific embodiment, the electrolyte comprises atleast one (oligo)ether of the general chemical formula (1):

R₁₁R₁₂R₁₃C—(CR₁₄R₁₅)_(x1)—[O—(CR₃₁R₃₂)_(a)—(CR₃₃R₃₄)_(b)]_(c)—O—(CR₂₄R₂₅)_(x2)—CR₂₁R₂₂R₂₃

and/or at least one (mono)ether of the general chemical formula (2):

R₄₁R₄₂R₄₃C—(CR₄₄R₄₅)_(y1)—O—(CR₅₄R₅₅)_(y2)—CR₅₁R₅₂R₅₃

More particularly, the at least one ether may be an (oligo)ether of thegeneral chemical formula (1) and/or a (mono)ether of the generalchemical formula (2).

In the general chemical formula (1):

R₁₁R₁₂R₁₃C—(CR₁₄R₁₅)_(x1)—[O—(CR₃₁R₃₂)_(a)—(CR₃₃R₃₄)_(b)]_(c)—O—(CR₂₄R₂₅)_(x2)—CR₂₁R₂₂R₂₃

1≦c≦10, for example 1≦c≦5, especially 1≦c≦2 or ≦3, 1≦a≦5, for example1≦a≦2 and 0≦b≦5, for example 1≦b≦5, especially 1≦b≦2, where x₁ and x₂are each independently a number ≦0 and ≦5, for example ≦0 and ≦1 and ≦3or ≦2.

R₁₁ here is a carboxylic acid group (—CO₂H) or a carboxylic ester group,for example —CO₂CH₃ or —CO₂C₂H₅, or a hydroxyl group (—OH) or a thiolgroup (—SH) or a halogen atom, such as —F, —Cl, —Br, —I, for example —For —Cl, or a branched or cyclic alkyl group, for example —CH(CH₃)₂,—CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃, —C₆H₁₁, —CF(CF₃)₂,—CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂, —C(CF₃)₃ or —C₆F₁₁, or an alkenyl group,especially a substituted or cyclic alkenyl group, for example atrans-substituted or cis-substituted or fully substituted C—C doublebond unit, or an alkoxy group, especially a branched or cyclic alkoxygroup, for example —O—CH₃, —O—C₂H₅, —O-n-C₃H₇, —O-n-C₄H₉, —O—CH(CH₃)₂,—O—CH(CH₃)(C₂H₅), —O—CH₂—CH(CH₃)₂, —O—C(CH₃)₃, —O—C₆H₁₁, —O—CF₃,—O—C₂F₅, —O-n-C₃F₇, —O-n-C₄F₉, —O—CF(CF₃)₂, —O—CF(CF₃)(C₂F₅),—O—CF₂—CF(CF₃)₂, —O—C(CF₃)₃ or —O—C₆F₁₁, or an aryl group, for example—C₆H₅ or —C₆F₅, or a heteroaryl group, or an aryloxy group, for example—O—C₆H₅ or —O—C₆F₅, or a heteroaryloxy group, where R₁₂ and R₁₃ are eachindependently hydrogen or a carboxylic acid group or a carboxylic estergroup or a halogen atom or an alkyl group or an alkenyl group or analkoxy group or an aryl group or a heteroaryl group or an aryloxy groupor a heteroaryloxy group, for example —H, —CO₂H, —CO₂CH₃, —CO₂C₂H₅, —F,—Cl, —Br, —I, —CH₃, —C₂H₅, -n-C₃H₇, -n-C₄H₉, —CH(CH₃)₂, —CH(CH₃)(C₂H₅),—CH₂—CH(CH₃)₂, —C(CH₃)₃, —C₆H₁₁, —CF₃, -n-C₃F₇, -n-C₄F₉, (CF₃)₂,—CF(CF₃)(C₃F₅), —CF₂—CF(CF₃)₂, —C(CF₃)₃, —C₆F₁₁, —O—CH₃, —O—C₂H₅,—O-n-C₃H₇, —O-n-C₄H₉, —O—CH(CH₃)₂, —O—CH(CH₃)(C₂H₅), —O—CH₂—CH(CH₃)₂,—O—C(CH₃)₃, —O—C₆H₁₁, —O—CF₃, —O—C₂F₅, —O-n-C₃F₇, —O-n-C₄F₉,—O—CF(CF₃)₂, —O—CF(CF₃)(C₂F₅), —O—CF₂—CF(CF₃)₂, —O—C(CF₃)₃, —O—C₆F₁₁,—C₆H₅, —C₆F₅, —O—C₆H₅ or —O—C₆F₅, or —CR₁₁R₁₂R₁₃ is a branched alkylgroup, for example —CH(CH₃)₂, —CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃,—CF(CF₃)₂, —CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂ or —C(CF₃)₃, or a cyclic alkylgroup, for example —C₆H₁₁ or —C₆F₁₁, or an alkenyl group, especially asubstituted or cyclic alkenyl group, for example a trans-substituted orcis-substituted or fully substituted C—C double bond unit, or an arylgroup, for example —C₆H₅ or —C₆F₅, or a heteroaryl group.

R₂₁, R₂₂, R₂₃ here are each independently hydrogen or a carboxylic acidgroup or a carboxylic ester group or a halogen atom or an alkyl group oran alkenyl group or an alkoxy group or an aryl group or a heteroarylgroup or an aryloxy group or a heteroaryloxy group, for example —H,—CO₂H, —CO₂CH₃, —CO₂C₂H₅, —F, —Cl, —Br, —I, —CH₃, —C₂H₅, -n-C₃H₇,-n-C₄H₉, —CH(CH₃)₂, —CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃, —C₆H₁₁,—CF₃, —C₂F₅, -n-C₃F₇, -n-C₄F₉, —CF(CF₃)₂, —CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂,—C(CF₃)₃, —C₆F₁₁, —O—CH₃, —O—C₂H₅, —O-n-C₃H₇, —O-n-C₄H₉, —O—CH(CH₃)₂,—O—CH(CH₃)(C₂H₅), —O—CH₂—CH(CH₃)₂, —O—C(CH₃)₃, —O—C₆H₁₁, —O—CF₃,—O—C₂F₅, —O-n-C₃F₇, —O-n-C₄F₉, —O—CF(CF₃)₂, —O—CF(CF₃)(C₂F₅),—O—CF₂—CF(CF₃)₂, —O—C(CF₃)₃, —O—C₆F₁₁, —C₆H₅, —C₆F₅, —O—C₆H₅ or —O—C₆F₅,or —CR₂₁R₂₂R₂₃ is a branched alkyl group, for example —CH(CH₃)₂,—CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃, —CF(CF₃)₂, —CF(CF₃)(C₂F₅),—CF₂—CF(CF₃)₂ or —C(CF₃)₃, or a cyclic alkyl group, for example —C₆H₁₁or —C₆F₁₁, or an alkenyl group, especially a substituted or cyclicalkenyl group, for example a trans-substituted or cis-substituted orfully substituted C—C double bond unit, or an aryl group, for example—C₆H₅ or —C₆F₅, or a heteroaryl group.

R₁₄, R₁₅, R₃₁, R₃₂, R₃₃, R₃₄, R₂₄, R₂₃ here are each independentlyhydrogen or a carboxylic acid group or a carboxylic ester group or ahalogen atom or an alkyl group or an alkenyl group or an alkoxy group oran aryl group or a heteroaryl group or an aryloxy group or aheteroaryloxy group, for example —H, —CO₂H, —CO₂CH₃, —CO₂C₂H₅, —F, —Cl,—Br, —I, —CH₃, —C₂H₅, -n-C₃H₇, -n-C₄H₉, —CH(CH₃)₂, —CH(CH₃)(C₂H₅),—CH₂—CH(CH₃)₂, —C(CH₃)₃, —C₆H₁₁, —CF₃, —C₂F₅, -n-C₃F₇, -n-C₄F₉,—CF(CF₃)₂, —CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂, —C(CF₃)₃, —C₆F₁₁, —O—CH₃,—O—C₂H₅, —O-n-C₃H₇, —O-n-C₄H₉, —O—CH(CH₃)₂, —O—CH(CH₃)(C₂H₅),—O—CH₂—CH(CH₃)₂, —O—C(CH₃)₃, —O—C₆H₁₁, —O—CF₃, —O—C₂F₅, —O-n-C₃F₇,—O-n-C₄F₉, —O—CF(CF₃)₂, —O—CF(CF₃)(C₂F₅), —O—CF₂—CF(CF₃)₂, —O—C(CF₃)₃,—O—C₆F₁₁, —C₆H₅, —C₆F₅, —O—C₆H₅ or —O—C₆F₅.

The viscosity of ethers of this kind is dependent on the structurethereof, but may advantageously especially be below 1.9 mPa*s, forexample within a range from about ≧0.3 mPa*s to ≦0.6 mPa*s.

More particularly, R₁₁ may be a carboxylic acid group or a carboxylicester group or a hydroxyl group or a thiol group or a halogen atom or abranched or cyclic alkyl group or an alkenyl group, especially asubstituted or cyclic alkenyl group, or an aryl group, and R₁₂ and R₁₃may each independently be hydrogen or a carboxylic acid group or acarboxylic ester group or a halogen atom or an alkyl group or an alkenylgroup or an aryl group, or —CR₁₁R₁₂R₁₃ may be a branched alkyl group ora cyclic alkyl group or an alkenyl group, especially a substituted orcyclic alkenyl group, or an aryl group.

In the context of one embodiment, in the general formula (1), R₁₁ is—CO₂H, —CO₂CH₃, —CO₂C₂H₅, —OH, —SH, —F, —CH(CH₃)₂, —CH(CH₃)(C₂H₅),—CH₂—CH(CH₃)₂, —C(CH₃)₃, —C₆H₁₁, —CF(CF₃)₂, —CF(CF₃)(C₂F₅),—CF₂—CF(CF₃)₂, —C(CF₃)₃, —C₆F₁₁, —C₆H₅ or —C₆F₅, especially —CO₂H,—CO₂CH₃, —CO₂C₂H₅, OH or —SH, for example —CO₂M, —CO₂CH₃, —CO₂C₂H₅ or—CR₁₁R₁₂R₁₃ is —CH(CH₃)₂, —CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃,—CF(CF₃)₂, —CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂, —C(CF₃)₃, —C₆H₁₁, —C₆F₁₁,—C₆H₅ or —C₆F₅, especially —CH(CH₃)₂, —CH₂—CH(CH₃)₂, —CH(CH₃)(C₂H₅),—C(CH₃)₃ or —C₆H₅.

As already elucidated, polar groups such as —CO₂H, —CO₂CH₃, —CO₂C₂H₅,—OH, —SH, —F can improve the lithium solvation or coordinationpropensity, and sterically demanding groups such as —CH(CH₃)₂,—CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃ and such as cyclic alkyl groups,for example —C₆F₁₁ or —C₆H₅, or branched or cyclic alkenyl groups, canreduce the viscosity. These properties can advantageously also beimproved by groups which are sterically demanding and polar in equalmeasure, such as —CF(CF₃)₂, —CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂, —C(CF₃)₃,—C₆F₁₁ or —C₆F₅.

In the context of a further embodiment, in the general chemical formula(1), R₂₁ is a carboxylic acid group (—CO₂H) or a carboxylic ester group,for example —CO₂CH₃ or —CO₂C₂H₅, or a hydroxyl group (—OH) or a thiolgroup (—SH) or a halogen atom, such as —F, —Cl, —Br, —I, for example —For —Cl, or a branched or cyclic alkyl group, for example —CH(CH₃)₂,—CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃, —C₆H₁₁, —CF(CF₃)₂,—CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂, —C(CF₃)₃ or —C₆F₁₁, or an alkenyl group,especially a substituted or cyclic alkenyl group, for example atrans-substituted or cis-substituted or fully substituted C—C doublebond unit, or an alkoxy group, especially a branched or cyclic alkoxygroup, for example —O—CH₃, —O—C₂H₅, —O-n-C₃H₇, —O-n-C₄H₉, —O—CH(CH₃)₂,—O—CH(CH₃)(C₂H₅), —O—CH₂—CH(CH₃)₂, —O—C(CH₃)₃, —O—C₆H₁₁, —O—CF₃,—O—C₂F₅, —O-n-C₃F₇, —O-n-C₄F₉, —O—CF(CF₃)₂, —O—CF(CF₃)(C₂F₅),—O—CF₂—CF(CF₃)₂, —O—C(CF₃)₃ or —O—C₆F₁₁, or an aryl group, for example—C₆H₅ or —C₆F₅, or a heteroaryl group, or an aryloxy group, for example—O—C₆H₅ or —O—C₆F₅, or a heteroaryloxy group, and R₂₂ and R₂₃ are eachindependently hydrogen or a carboxylic acid group or a carboxylic estergroup or a halogen atom or an alkyl group or an alkenyl group or analkoxy group or an aryl group or a heteroaryl group or an aryloxy groupor a heteroaryloxy group, for example —H, —CO₂H, —CO₂CH₃, —CO₂C₂H₅, —F,—Cl, —Br, —I, —CH₃, —C₂H₅, -n-C₃H₇, -n-C₄H₉, —CH(CH₃)₂, —CH(CH₃)(C₂H₅),—CH₂—CH(CH₃)₂, —C(CH₃)₃, —C₆H₁₁, —CF₃, —C₂F₃, -n-C₃F₇, -n-C₄F₉,—CF(CF₃)₂, —CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂, —C(CF₃)₃, —C₆F₁₁, —O—CH₃,—O—C₂H₅, —O-n-C₃H₇, —O-n-C₄H₉, —O—CH(CH₃)₂, —O—CH(CH₃)(C₂H₅),—O—CH₂—CH(CH₃)₂, —O—C(CH₃)₃, —O—C₆H₁₁, —O—CF₃, —O—C₂F₅, —O-n-C₃F₇,—O-n-C₄F₉, —O—CF(CF₃)₂, —O—CF(CF₃)(C₂F₅), —O—CF₂—CF(CF₃)₂, —O—C(CF₃)₃,—O—C₆F₁₁, —C₆H₅, —C₆F₅, —O—C₆H₅ or —O—C₆F₅, or —CR₂₁R₂₂R₂₃ is a branchedalkyl group, for example —CH(CH₃)₂, —CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂,—C(CH₃)₃, —CF(CF₃)₂, —CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂ or —C(CF₃)₃, or acyclic alkyl group, for example —C₆H₁₁ or —C₆F₁₁, or an alkenyl group,especially a substituted or cyclic alkenyl group, for example atrans-substituted or cis-substituted or fully substituted C—C doublebond unit, or an aryl group, for example —C₆H₅ or —C₆F₅, or a heteroarylgroup.

It is thus advantageously possible to further improve the lithiumsolvation or coordination propensity and/or further reduce theviscosity.

More particularly, R₂₁ may be a carboxylic acid group or a carboxylicester group or a hydroxyl group or a thiol group or a halogen atom or abranched or cyclic alkyl group or an alkenyl group, especially asubstituted or cyclic alkenyl group, or an aryl group, and R₂₂ and R₂₃may each independently be hydrogen or a carboxylic acid group or acarboxylic ester group or a halogen atom or an alkyl group or an alkenylgroup or an aryl group, or —CR₂₁R₂₂R₂₃ may be a branched alkyl group ora cyclic alkyl group or an alkenyl group, especially a substituted orcyclic alkenyl group, or an aryl group.

In principle, R₂₁ may be identical to or different than R₁₁, and—CR₂₁R₂₂R₂₃ may be identical to or different than —CR₁₁R₁₂R₁₃

In the context of a further embodiment, in the general chemical formula(1), however, R₂₁ is identical to R₁₁ or —CR₂₁R₂₂R₂₃ is identical to—CR₁₁R₁₂R₁₃

In the context of a further embodiment, in the general chemical formula(1), R₃₁ and/or R₃₃ and/or R₁₂ and/or R₁₄ and/or R₂₂ and/or R₂₄ is/arean alkyl group, by way of example —CH₃, —C₂H₅, -n-C₃H₇, -n-C₄H₉,—CH(CH₃)₂, —CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃, —C₆H₁₁, —CF₃, —C₂F₅,-n-C₃F₇, -n-C₄F₉, —CF(CF₃)₂, —CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂, —C(CF₃)₃ or—C₆F₁₁, for example —CH₃ or —C₂H₅. In this way, it is advantageouslypossible to introduce sterically demanding groups into the structure ofthe (oligo)ether, in order to reduce the viscosity.

R₃₂ and/or R₃₄ and/or R₁₃ and/or R₁₅ and/or R₂₃ and/or R₂₅ here mayespecially be hydrogen or likewise an alkyl group, by way of example —H,—CH₃, —C₂H₅, -n-C₃H₇, -n-C₄H₉, —CH(CH₃)₂, —CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂,—C(CH₃)₃, —C₆H₁₁, —CF₃, —C₂F₅, -n-C₃F₇, -n-C₄F₉, —CF(CF₃)₂,—CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂, —C(CF₃)₃ or —C₆F₁₁, for example —H or—CH₃ or —C₂H₅. Alkyl groups can advantageously further increase thesteric demands of the structure of the (oligo)ether and especiallyfurther reduce the viscosity.

In the context of one configuration, R₃₂ and/or R₃₄ and/or R₁₃ and/orR₁₅ and/or R₂₃ and/or R₂₅, however, are hydrogen (—H). Since one alkylsubstituent per carbon atom, which may already be provided, for example,as R₃₁ and/or R₃₃ and/or R₁₂ and/or R₁₄ and/or R₂₂ and/or R₂₄, may besufficient in some cases for attainment of a suitable viscosity, thesecond substituent can optionally be simply maintained and be hydrogen.

Examples of symmetric (oligo)ethers of the general formula (1) are:

By way of example of the numerous symmetric (oligo)-ethers of thegeneral formula (1) which may be based on a combination of thestructural elements shown in the preceding examples, especially havingtwo different terminal substituents among those shown above, thefollowing asymmetric (oligo)ether of the general formula (1) is shown:

In the general chemical formula (2):

R₄₁R₄₂R₄₃C—(CR₄₄R₄₅)_(y1)—O—(CR₅₄R₅₅)_(y2)—CR₅₁R₅₂R₅₃

y₁ and y₂ are each independently a number ≧0 and ≦5, for example ≧0 or≧1 and ≦3 and ≦2.

R₄₁ here is a carboxylic acid group (—CO₂M) or a carboxylic ester group,for example —CO₂CH₃ or —CO₂C₂H₅, or a hydroxyl group (—OH) or a thiolgroup (—SH) or a halogen atom, such as —F, —Cl, —Br, —I, for example —For —Cl, or a branched or cyclic alkyl group, for example —CH(CH₃)₂,—CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃, —C₆H₁₁, (CF₃)₂, —CF(CF₃)(C₂F₅),—CF₂—CF(CF₃)₂, —C(CF₃)₃ or —C₆F₁₁, or an alkenyl group, especially asubstituted or cyclic alkenyl group, for example a trans-substituted orcis-substituted or fully substituted C—C double bond unit, or an alkoxygroup, especially a branched or cyclic alkoxy group, for example —O—CH₃,—O—C₂H₅, —O-n-C₃H₇, —O-n-C₄H₉, —O—CH(CH₃)₂, —O—CH(CH₃)(C₂H₅),—O—CH₂—CH(CH₃)₂, —O—C(CH₃)₃, —O—C₆H₁₁, —O—CF₃, —O—C₂F₅, —O-n-C₃F₇,—O-n-C₄F₉, —O—CF(CF₃)₂, —O—CF(CF₃)(C₂F₅)—O—CF₂—CF(CF₃)₂, —O—C(CF₃)₃ or—O—C₆F₁₁, or an aryl group, for example —C₆H₅ or —C₆F₅, or a heteroarylgroup, or an aryloxy group, for example —O—C₆H₅ or —O—C₆F₅, or aheteroaryloxy group, where R₄₂ and R₄₃ are each independently hydrogenor a carboxylic acid group or a carboxylic ester group or a halogen atomor an alkyl group or an alkenyl group or an alkoxy group or an arylgroup or a heteroaryl group or an aryloxy group or a heteroaryloxygroup, for example —H, —CO₂M, —CO₂CH₃, —CO₂C₂H₅, —F, —Cl, —Br, —I, —CH₃,—C₂H₅, -n-C₃H₇, -n-C₄H₉, —CH(CH₃)₂, —CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂,—C(CH₃)₃, —C₆H₁₁, —CF₃, —C₂F₅, -n-C₃F₇, -n-C₄F₉, —CF(CF₃)₂,—CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂, —C(CF₃)₃, —C₆F₁₁, —O—CH₃, —O—C₂H₅,—O-n-C₃H₇, —O-n-C₄H₉, —O—CH(CH₃)₂, —O—CH(CH₃)(C₂H₃)—O—CH₂—CH(CH₃)₂,—O—C(CH₃)₃, —O—C₆H₁₁, —O—CF₃, —O—C₂F₅, —O-n-C₃F₇, —O-n-C₄F₉,—O—CF(CF₃)₂, —O—CF(CF₃)(C₂F₅), —O—CF₂—CF(CF₃)₂, —O—C(CF₃)₃, —O—C₆F₁₁,—C₆H₅, —C₆F₅, —O—C₆H₅ or —O—C₆F₅, or —CR₁₁R₄₂R₄₃ is a branched alkylgroup, for example —CH(CH₃)₂, —CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃,—CF(CF₃)₂, —CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂ or —C(CF₃)₃, or a cyclic alkylgroup, for example —C₆H₁₁ or —C₆F₁₁, or an alkenyl group, especially asubstituted or cyclic alkenyl group, for example a trans-substituted orcis-substituted or fully substituted C—C double bond unit, or an arylgroup, for example —O—C₆H₅ or —O—C₆F₅, or a heteroaryl group.

R₅₁, R₅₂, R₅₃ here are each independently hydrogen or a carboxylic acidgroup or a carboxylic ester group or a halogen atom or an alkyl group oran alkenyl group or an alkoxy group or an aryl group or a heteroarylgroup or an aryloxy group or a heteroaryloxy group, for example —H,—CO₂H, —CO₂CH₃, —CO₂C₂H₅, —F, —Cl, —Br, —I, —CH₃, —C₂H₅, -n-C₃H₇,-n-C₄H₉, —CH(CH₃)₂, —CH(CH₃)(C₂H₅). —CH₂—CH(CH₃)₂, —C(CH₃)₃, —C₆H₁₁,—CF₃, —C₂F₅, -n-C₃F₇, -n-C₄F₉, —CF(CF₃)₂, —CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂,—C(CF₃)₃, —C₆F₁₁, —O—CH₃, —O—C₂H₅, —O-n-C₃H₇, —O-n-C₄H₉, —O—CH(CH₃)₂,—O—CH(CH₃)(C₂H₅), —O—CH₂—CH(CH₃)₂, —O—C(CH₃)₃, —O—C₆H₁₁, —O—CF₃,—O—C₂F₅, —O-n-C₃F₇, —O-n-C₄F₉, —O—CF(CF₃)₂, —O—CF(CF₃)(C₂F₅),—O—CF₂—CF(CF₃)₂, —O—C(CF₃)₃, —O—C₆F₁₁, —C₆H₅, —C₆F₅, —O—C₆H₅ or —O—C₆F₅,or —CR₅₁R₅₂R₅₃ is a branched alkyl group, for example —CH(CH₃)₂,—CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃, —CF(CF₃)₂, —CF(CF₃)(C₂F₅),—CF₂—CF(CF₃)₂ or —C(CF₃)₃, or a cyclic alkyl group, for example —C₆H₁₁or —C₆F₁₁, or an alkenyl group, especially a substituted or cyclicalkenyl group, for example a trans-substituted or cis-substituted orfully substituted C—C double bond unit, or an aryl group, for example—O—C₆H₅ or —O—C₆F₅, or a heteroaryl group.

R₄₄, R₄₅, R₅₄ and R₅₅ here are each independently hydrogen or acarboxylic acid group or a carboxylic ester group or a halogen atom oran alkyl group or an alkenyl group or an alkoxy group or an aryl groupor a heteroaryl group or an aryloxy group or a heteroaryloxy group, forexample —H, —CO₂H, —CO₂CH₃, —CO₂C₂H₅, —F, —Cl, —Br, —I, —CH₃, —C₂H₅,n-C₃H₇, -n-C₄H₉, —CH(CH₃)₂, —CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃,—C₆H₁₁, —CF₃, —C₂F₅, -n-C₃F₇, -n-C₄F₉, —CF(CF₃)₂, —CF(CF₃)(C₂F₅),—CF₂—CF(CF₃)₂, —C(CF₃)₃, —C₆F₁₁, —O—CH₃, —O—C₂H₅, —O-n-C₃H₇, —O-n-C₄H₉,—O—CH(CH₃)₂, —O—CH(CH₃)(C₂H₅), —O—CH₂—CH(CH₃)₂, —O—C(CH₃)₃, —O—C₆H₁₁,—O—CF₃, —O—C₂F₅, —O-n-C₃F₇, —O-n-C₄F₉, —O—CF(CF₃)₂, —O—CF(CF₃)(C₂F₅),—O—CF₂—CF(CF₃)₂, —O—C(CF₃)₃, —O—C₆F₁₁, —C₆H₅, —C₆F₅, —O—C₆H₅ or —O—C₆F₅.

The viscosity of ethers of this kind is dependent on the structurethereof, but may advantageously especially be below 1.9 mPa*s, forexample within a range from about ≧0.3 mPa*s to ≦0.6 mPa*s.

More particularly, R₄₁ may be a carboxylic acid group or a carboxylicester group or a hydroxyl group or a thiol group or a halogen atom or abranched or cyclic alkyl group or an alkenyl group, especially asubstituted or cyclic alkenyl group, or an aryl group, and R₄₂ and/orR₄₃ may each independently be hydrogen or a carboxylic acid group or acarboxylic ester group or a halogen atom or an alkyl group or an alkenylgroup or an aryl group, or —CR₄₁R₄₂R₄₃ may be a branched alkyl group ora cyclic alkyl group or an alkenyl group, especially a substituted orcyclic alkenyl group, or an aryl group.

In the context of one embodiment, in the general chemical formula (2),R₄₁ is —CO₂H, —CO₂CH₃, —CO₂C₂H₅, —OH, —SH, —F, —CH(CH₃)₂,—CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃, —C₆H₁₁, —CF(CF₃)₂,—CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂, —C(CF₃)₃, —C₆F₁₁, —C₆H₅ or —C₆F₅,especially —CO₂H, —CO₂CH₃, —CO₂C₂H₅, —OH, —SH, —F, —C₆H₁₁, —C₆F₁₁, —C₆H₅or —C₆F₅, for example —CO₂H, —CO₂CH₃, —CO₂C₂H₅, OH or —SH, for example—CO₂H, —CO₂CH₃, —CO₂C₂H₅ or —SH, or —CR₄₁R₄₂R₄₃ is —CH(CH₃)₂,—CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃, —CF(CF₃)₂, —CF(CF₃)(C₂F₅),—CF₂—CF(CF₃)₂, —C(CF₃)₃, —C₆H₁₁, —C₆F₁₁, —C₆H₅ or —C₆F₅, especially—CH(CH₃)₂, —CH₂—CH(CH₃)₂, —CH(CH₃)(C₂H₅), —C(CH₃)₃ or —C₆H₅, for example—C₆H₁₁, —C₆F₁₁, —C₆H₅ or —C₆F₅.

As already elucidated, polar groups such as —CO₂H, —CO₂CH₃, —CO₂C₂H₅,—OH, —SH, —F can improve the lithium solvation or coordinationpropensity, and sterically demanding groups such as —CH(CH₃)₂,—CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃ and such as cyclic alkyl groups,for example —C₆F₁₁ or —C₆H₅, or branched or cyclic alkenyl groups, canreduce the viscosity. These properties can advantageously also beimproved by groups which are sterically demanding and polar in equalmeasure, such as —CF(CF₃)₂, —CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂, —C(CF₃)₃,—C₆F₁₁ or —C₆F₅.

In the context of a further embodiment, in the general chemical formula(2), R₅₁ is a carboxylic acid group (—CO₂H) or a carboxylic ester group,for example —CO₂CH₃ or —CO₂C₂H₅, or a hydroxyl group (—OH) or a thiolgroup (—SH) or a halogen atom, such as —F, —Cl, —Br, —I, for example —For —Cl, or a branched or cyclic alkyl group, for example —CH(CH₃)₂,—CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃, —C₆H₁₁, —CF(CF₃)₂,—CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂, —C(CF₃)₃ or —C₆F₁₁, or an alkenyl group,especially a substituted or cyclic alkenyl group, for example atrans-substituted or cis-substituted or fully substituted C—C doublebond unit, or an alkoxy group, especially a branched or cyclic alkoxygroup, for example —O—CH₃, —O—C₂H₅, —O-n-C₃H₇, —O-n-C₄H₉, —O—CH(CH₃)₂,—O—CH(CH₃)(C₂H₅), —O—CH₂—CH(CH₃)₂, —O—C(CH₃)₃, —O—C₆H₁₁, —O—CF₃,—O—C₂F₅, —O-n-C₃F₇, —O-n-C₄F₉, —O—CF(CF₃)₂, —O—CF(CF₃)(C₂F₅),—O—CF₂—CF(CF₃)₂, —O—C(CF₃)₃ or —O—C₆F₁₁, or an aryl group, for example—C₆H₅ or —C₆F₅, or a heteroaryl group, or an aryloxy group, for example—O—C₆H₅ or —O—C₆F₅, or a heteroaryloxy group, and R₅₂ and R₅₃ are eachindependently hydrogen or a carboxylic acid group or a carboxylic estergroup or a halogen atom or an alkyl group or an alkenyl group or analkoxy group or an aryl group or a heteroaryl group or an aryloxy groupor a heteroaryloxy group, for example —H, —CO₂H, —CO₂CH₃, —CO₂C₂H₅, —F,—Cl, —Br, —I, —CH₃, —C₂H₅, -n-C₃H₇, -n-C₄H₉, —CH(CH₃)₂, —CH(CH₃)(C₂H₅),—CH₂—CH(CH₃)₂, —C(CH₃)₃, —C₆H₁₁, —CF₃, —C₂F₅, -n-C₃F₇, -n-C₄F₉,—CF(CF₃)₂, —CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂, —C(CF₃)₃, —C₆F₁₁, —O—CH₃,—O—C₂H₅, —O-n-C₃H₇, —O-n-C₄H₉, —O—CH(CH₃)₂, —O—CH(CH₃)(C₂H₅),—O—CH₂—CH(CH₃)₂, —O—C(CH₃)₃, —O—C₆H₁₁, —O—CF₃, —O—C₂F₅, —O-n-C₃F₇,—O-n-C₄F₉, —O—CF(CF₃)₂, —O—CF(CF₃)(C₂F₅), —O—CF₂—CF(CF₃)₂, —O—C(CF₃)₃,—O—C₆F₁₁, —C₆H₅, —C₆F₅, —O—C₆H₅ or —O—C₆F₅, or —CR₅₁R₅₂R₅₃ is a branchedalkyl group, for example —CH(CH₃)₂, —CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂,—C(CH₃)₃, —CF(CF₃)₂, —CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂ or —C(CF₃)₃, or acyclic alkyl group, for example —C₆H₁₁ or —C₆F₁₁, or an alkenyl group,especially a substituted or cyclic alkenyl group, for example atrans-substituted or cis-substituted or fully substituted C—C doublebond unit, or an aryl group, for example —C₆H₅ or —C₆F₅, or a heteroarylgroup.

It is thus advantageously possible to further improve the lithiumsolvation or coordination propensity and/or further reduce theviscosity.

More particularly, R₅₁ may be a carboxylic acid group or a carboxylicester group or a hydroxyl group or a thiol group or a halogen atom or abranched or cyclic alkyl group or an alkenyl group, especially asubstituted or cyclic alkenyl group, or an aryl group, and R₅₂ and R₅₃may each independently be hydrogen or a carboxylic acid group or acarboxylic ester group or a halogen atom or an alkyl group or an alkenylgroup or an aryl group, or —CR₅₁R₅₂R₅₃ may be a branched alkyl group ora cyclic alkyl group or an alkenyl group, especially a substituted orcyclic alkenyl group, or an aryl group.

In principle, R₅₁ may be identical to or different than R₄₁, and—CR₅₁R₅₂R₅₃ may be identical to or different than —CR₄₁R₄₂R₄₃

In the context of a further embodiment, in the general chemical formula(2), however, R₅₁ is identical to R₄₁ or —CR₅₁R₅₂R₅₃ is identical to—CR₄₁R₄₂R₄₃

In the context of a further embodiment, in the general chemical formula(2), R₄₂ and/or R₄₄ and/or R₅₂ and/or R₅₄ is/are an alkyl group, by wayof example —CH₃, —C₂H₅, -n-C₃H₇, -n-C₄H₉, —CH(CH₃)₂, —CH(CH₃)(C₂H₅),—CH₂—CH(CH₃)₂, —C(CH₃)₃, —C₆H₁₁, —CF₃, —C₂F₃, -n-C₃F₇, -n-C₄F₉,—CF(CF₃)₂, —CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂, —C(CF₃)₃ or —C₆F₁₁, forexample —CH₃ or —C₂H₅. In this way, it is advantageously possible tointroduce sterically demanding groups into the structure of the(mono)ether, in order to reduce the viscosity.

R₄₃ and/or R₄₅ and/or R₅₃ and/or R₅₅ here may especially be hydrogen orlikewise an alkyl group, by way of example —H, —CH₃, —C₂H₃, -n-C₃H₇,-n-C₄H₉, —CH(CH₃)₂, —CH(CH₃)(C₂H₃), —CH₂—CH(CH₃)₂, —C(CH₃)₃, —C₆H₁₁,—CF₃, —C₂F₅, -n-C₃F₇, -n-C₄F₉, —CF(CF₃)₂, —CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂,—C(CF₃)₃ or —C₆F₁₁, for example —H or —CH₃ or —C₂H₅. Alkyl groups canadvantageously further increase the steric demands of the structure ofthe (mono)ether and especially further reduce the viscosity.

In the context of one configuration, R₄₃ and/or R₄₅ and/or R₅₃ and/orR₅₅ are hydrogen (—H). Since one alkyl substituent per carbon atom,which may already be provided, for example, as R₄₂ and/or R₄₄ and/or R₅₂and/or R₅₄, may be sufficient in some cases for attainment of a suitableviscosity, the second substituent can optionally be simply maintainedand be hydrogen.

Examples of Symmetric (Mono)Ethers of the General Formula (2) are:

By way of example of the numerous a symmetric (mono)-ethers of thegeneral formula (2) which may be based on a combination of thestructural elements shown in the preceding examples, especially havingtwo different terminal substituents among those shown above, thefollowing asymmetric (mono)ethers of the general formula (2) are shown:

With regard to further technical features and advantages of theelectrolyte of the invention, reference is hereby made explicitly to theelucidations in connection with the electrolyte solvent of theinvention, the electrolyte additive of the invention, the ethers of theinvention, the uses of the invention, the lithium cell or battery of theinvention, and to the figures and the description of the figures.

The present invention further provides an electrolyte solvent or anelectrolyte additive, especially for a lithium cell/battery, comprisingat least one (oligo)ether of the general chemical formula (1):R₁₁R₁₂R₁₃C—(CR₁₄R₁₅)_(x1)—[O—(CR₃₁R₃₂)_(a)—(CR₃₃R₃₄)_(b)]_(c)—O—(CR₂₄R₂₅)_(x2)—CR₂₁R₂₂R₂₃and/or at least one (mono)ether of the general chemical formula (2):R₄₁R₄₂R₄₃C—(CR₄₄R₄₅)_(y1)—O—(CR₅₄R₅₅)_(y2)—CR₅₁R₅₂R₅₃, or an(oligo)ether of the general chemical formula (1):R₁₁R₁₂R₁₃C—(CR₁₄R₁₅)_(x1)—[O—(CR₃₁R₃₂)_(a)—(CR₃₃R₃₄)_(b)]_(c)—O—(CR₂₄R₂₅)_(x2)CR₂₁R₂₂R₂₃ and/or one (mono) ether of the general chemical formula (2):R₄₁R₄₂R₄₃C—(CR₄₄R₄₅)_(y1)—O—(CR₅₄R₅₅)_(y2)—CR₅₁R₅₂R₅₃, and also(oligo)ethers of the general chemical formula (1):R₁₁R₁₂R₁₃C(CR₁₄R₁₅)_(x1)[O—(CR₃₁R₃₂)_(a)—(CR₃₃R₃₄)_(b)]_(c)—O—(CR₂₄R₂₅)_(x2)—CR₂₁R₂₂R₂₃and/or (mono)-ethers of the general chemical formula (2):R₄₁R₄₂R₄₃C—(CR₄₄R₄₅)_(y1)—O—(CR₅₄R₅₅)_(y2)—CR₅₁R₅₂R₅₃, and the usethereof as electrolyte solvent and/or electrolyte additive.

The substituents R₁₁, R₁₂, R₁₃, R₁₄, R₁₅, R₂₁, R₂₂, R₂₃, R₂₄, R₂₅, R₃₁,R₃₂, R₃₃, R₃₄ or R₄₁, R₄₂, R₄₃, R₄₄, R₄₅, R₅₁, R₅₂, R₅₃, R₅₄, R₅₅ may inprinciple have the same meaning as the meanings elucidated in connectionwith the electrolyte of the invention and the specific embodimentsthereof for the substituents R₁₁, R₁₂, R₁₃, R₁₄, R₁₅, R₂₁, R₂₂, R₂₃,R₂₄, R₂₅, R₃₁, R₃₂, R₃₃, R₃₄ or R₄₁, R₄₂, R₄₃, R₄₄, R₄₅, R₅₁, R₅₂, R₅₃,R₅₄, R₅₅.

The electrolyte solvent or electrolyte additive may in principlecomprise the at least one (oligo)ether of the general chemical formula(1) and/or the at least one (mono)ether of the general chemical formula(2) either as main solvent or main constituent or as cosolvent orsecondary constituent, or else consist of the at least one (oligo)etherof the general chemical formula (1) or the at least one (mono)ether ofthe general chemical formula (2) or a mixture thereof.

The electrolyte solvent may comprise, for example, based on the totalweight thereof, ≧0.1% by weight to ≦20% by weight, for example >2% byweight to ≦20% by weight, especially ≧5% by weight to ≦10% by weight, or≧0.5% by weight to ≦2% by weight, of ethers of the general chemicalformula (1) and (2) (in total).

As well as the at least one ether of the general chemical formula (1)and/or (2), the electrolyte solvent may comprise, for example, at leastone further solvent, for example at least one cyclic carbonate and/or atleast one acyclic carbonate. For example, the electrolyte solvent, basedon the total weight thereof, may comprise ≧15% by weight to ≦40% byweight, especially ≧20% by weight to ≦35% by weight, for example ≧25% byweight to ≦30% by weight, of cyclic carbonates and/or ≧50% by weight to≦80% by weight, especially ≧55% by weight to ≦75% by weight, for example≧60% by weight to ≦70% by weight, of acyclic carbonates and/or ≧0.1% byweight to ≦20% by weight, especially ≧5% by weight to ≦10% by weightand/or ≧0.5% by weight to ≦2% by weight, of ethers. For example, theelectrolyte solvent, based on the total weight thereof, may compriseabout 25% by weight of cyclic carbonates, for example ethylene carbonate(EC), about 70% by weight of acyclic carbonates and about 5% by weightof ethers of the general chemical formula (1) and/or (2), or about 25%by weight of cyclic carbonates, for example ethylene carbonate (EC),about 65% by weight of acyclic carbonates and about 10% by weight ofethers of the general chemical formula (1) and/or (2), or about 30% byweight of cyclic carbonates, for example ethylene carbonate (EC), about60% by weight of acyclic carbonates and about 10% by weight of ethers ofthe general chemical formula (1) and/or (2). For instance, theelectrolyte solvent may advantageously be endowed with good lithium ionsolvation or coordination and low viscosity.

The electrolyte additive used may be the at least one (oligo)ether ofthe general chemical formula (1) and/or the at least one (mono)ether ofthe general chemical formula (2), for example in such a way that it isadded to an electrolyte solvent or electrolyte solvent mixture in anamount within a range from ≧0.5% by weight to ≦2% by weight, based onthe total weight of solvent.

In the context of a specific embodiment, R₄₁ and/or R₅₁ or R₁₁ and/orR₂₁ is a carboxylic acid group (—CO₂H) or a carboxylic ester group, forexample —CO₂CH₃ or —CO₂C₂H₅, or a hydroxyl group (—OH) or a thiol group(—SH) or a halogen atom, such as —F, —Cl, —Br, —I, for example —F or—Cl, or a cyclic alkyl group, for example —C₆H₁₁ or —C₆F₁₁, or analkenyl group, especially a substituted or cyclic alkenyl group, forexample a trans-substituted or cis-substituted or fully substituted C—Cdouble bond unit, or an alkoxy group, especially a branched or cyclicalkoxy group, for example —O—CH₃, —O—C₂H₅, —O-n-C₃H₇, —O-n-C₄H₉,—O—CH(CH₃)₂, —O—CH(CH₃)(C₂H₃), —O—CH₂—CH(CH₃)₂, —O—C(CH₃)₃, —O—C₆H₁₁,—O—CF₃, —O—C₂F₅, —O-n-C₃F₇, —O-n-C₄F₉, —O—CF(CF₃)₂, —O—CF(CF₃)(C₂F₃),—O—CF₂—CF(CF₃)₂, —O—C(CF₃)₃ or —O—C₆F₁₁, or an aryl group, for example—C₆H₅ or —C₆F₅, or a heteroaryl group, or an aryloxy group, for example—O—C₆H₅ or —O—C₆F₅ or a heteroaryloxy group, and

R₄₂ and R₄₃ and/or R₅₂ and R₅₃ or R₁₂ and R₁₃ and/or R₂₂ and R₂₃ areeach independently hydrogen or a carboxylic acid group or a carboxylicester group or a halogen atom or an alkyl group or an alkenyl group oran alkoxy group or an aryl group or a heteroaryl group or an aryloxygroup or a heteroaryloxy group, for example —H, —CO₂H, —CO₂CH₃,—CO₂C₂H₅, —F, —Cl, —Br, —I, —CH₃, —C₂H₅, -n-C₃H₇, -n-C₄H₉, —CH(CH₃)₂,—CH(CH₃)(C₂H₅), —CH₂—CH(CH₃)₂, —C(CH₃)₃, —C₆H₁₁, —CF₃, —C₂F₅, -n-C₃F₇,-n-C₄F₉, —CF(CF₃)₂, —CF(CF₃)(C₂F₅), —CF₂—CF(CF₃)₂, —C(CF₃)₃, —C₆F₁₁,—O—CH₃, —O—C₂H₅, —O-n-C₃H₇, —O-n-C₄H₉, —O—CH(CH₃)₂, —O—CH(CH₃)(C₂H₅),—O—CH₂—CH(CH₃)₂, —O—C(CH₃)₃, —O—C₆H₁₁, —O—CF₃, —O—C₂F₅, —O-n-C₃F₇,—O-n-C₄F₉, —O—CF(CF₃)₂, —O—CF(CF₃)(C₂F₅), —O—CF₂—CF(CF₃)₂, —O—C(CF₃)₃,—O—C₆F₁₁, —C₆H₅, —C₆F₅, —O—C₆H₅ or —O—C₆F₅, or —CR₄₁R₄₂R₄₃ and/or—CR₅₁R₅₂R₅₃ or —CR₁₁R₁₂R₁₃ and/or —CR₂₁R₂₂R₂₃ is a cyclic alkyl group,for example —C₆H₁₁ or —C₆F₁₁, or an alkenyl group, especially asubstituted or cyclic alkenyl group, for example a trans-substituted orcis-substituted or fully substituted C—C double bond unit, or an arylgroup, for example —C₆H₅ or —C₆F₅, or a heteroaryl group.

In the context of a further specific embodiment, R₁₁ or R₂₁ is —CO₂H,—CO₂CH₃, —CO₂C₂H₅, —SH or —OH, or —CR₁₁R₁₂R₁₃ or —CR₂₁R₂₂R₂₃ is—CH(CH₃)₂, CH₂—CH(CH₃)₂, —CH(CH₃)(C₂H₅), —C(CH₃)₃, —C₆H₁₁, —C₆H₁₁, —C₆H₅or —C₆F₅. More particularly, R₂₁ and R₁₁ may be the same or —CR₂₁R₂₂R₂₃and —CR₁₁R₁₂R₁₃ may be the same.

In the context of a further specific embodiment, R₃₁ and/or R₃₃ and/orR₁₂ and/or R₁₄ and/or R₂₂ and/or R₂₄ are an alkyl group and where R₃₂and/or R₃₄ and/or R₁₃ and/or R₁₅ and/or R₂₃ and/or R₂₅ are hydrogen oran alkyl group.

In the context of a further specific embodiment, R₄₁ or R₅₁ is —CO₂H,—CO₂CH₃, —CO₂C₂H₅, —OH, —SH, —F, —C₆H₁₁, —C₆F₁₁, —C₆H₅ or —C₆F₅,especially —CO₂H, —CO₂CH₃, —CO₂C₂H₅, —OH or —SH, for example —CO₂H,—CO₂CH₃, —CO₂C₂H₅ or —SH, or —CR₄₁R₄₂R₄₃ or —CR₅₁R₅₂R₅₃ is —C₆H₁₁,—C₆F₁₁, —C₆H₅ or —C₆F₅. More particularly, R₄₁ or R₅₁ or —CR₄₁R₄₂R₄₃ and—CR₅₁R₅₂R₅₃ may be the same.

In the context of a further specific embodiment, R₄₂ and/or R₄₄ and/orR₅₂ and/or R₅₄ are an alkyl group and where R₄₃ and/or R₄₅ and/or R₅₃and/or R₅₅ are hydrogen or an alkyl group.

With regard to further technical features and advantages of theelectrolyte solvent of the invention, of the electrolyte additive of theinvention, of the ethers of the invention and the uses thereof,reference is hereby made explicitly to the elucidations in connectionwith the electrolyte of the invention, the lithium cell or battery ofthe invention, and the figures and the description of the figures.

The invention further relates to a lithium cell or lithium battery,especially a lithium ion cell or lithium ion battery, for example anelectric vehicle (EV), a hybrid or micro-hybrid or plug-in electricvehicle (HEV or μ-HEV or PHEV), a mobile, stationary and/or maritimeapplication, for example for a tool and/or garden appliance (power tool)or a consumer device, for example a cell phone, laptop/notebook, MP3player, which comprise an electrolyte of the invention and/or anelectrolyte solvent of the invention and/or an electrolyte additive ofthe invention and/or an ether of the invention. The lithium cell/batterymay especially have a negative electrode (anode) and a positiveelectrode (cathode). The negative electrode and the positive electrodemay be separated spatially from one another by a separator, for examplea porous separator, for example made from polyethylene and/orpolypropylene. The negative electrode may comprise graphite, forexample. The positive electrode may comprise, for example, a metal oxideand/or metal phosphate, for example lithium nickel cobalt manganeseoxide (NCM), lithium nickel cobalt aluminum oxide (NCA), lithium cobaltoxide, a spinel such as lithium manganese oxide (LiMn₂O₄) and/or lithiumiron phosphate (LiFePO₄).

With regard to further technical features and advantages of the lithiumcell or lithium battery of the invention, reference is hereby madeexplicitly to the elucidations in connection with the electrolyte of theinvention, the electrolyte solvent of the invention, the electrolyteadditive of the invention, the ethers of the invention, the uses of theinvention, and the figures and the description of the figures.

DRAWINGS

Further advantages and advantageous configurations of the subject matterof the invention are illustrated by the drawings and elucidated in thedescription which follows. It should be noted here that the drawings aremerely of descriptive character and are not intended to restrict theinvention in any way at all. The drawings show:

FIG. 1 a schematic view of a lithium ion cell during the chargingoperation; and

FIG. 2 a schematic view of the lithium ion cell shown in FIG. 1 duringthe discharging operation.

FIGS. 1 and 2 show that the lithium ion cell has an anode (negativeelectrode) 1 and a cathode (positive electrode) 2, separated spatiallyfrom one another by a porous separator 7, for example made frompolyethylene and/or polypropylene. The anode 1 may comprise, forexample, graphite (C₆) and the cathode 2 may comprise a metal oxide(LiMO₂, LiM_(y)O_(z)) and/or metal phosphate, for example lithium nickelcobalt manganese oxide (NCM), lithium nickel cobalt aluminum oxide(NCA), lithium cobalt oxide, a spinel such as lithium manganese oxide(LiMn₂O₄) and/or lithium iron phosphate (LiFePO₄).

FIGS. 1 and 2 show that the anode 1 is in contact with an anode outputconductor 5, for example made from copper, and the cathode 2 with acathode output conductor 6, for example made from aluminum. In thecontext of the diagram shown in FIGS. 1 and 2, the anode outputconductor 5 and the cathode output conductor 6 are electricallyconnected to one another via an ampere meter 8.

FIGS. 1 and 2 further indicate that the cell includes an electrolyte 3comprising an electrolyte solvent or electrolyte solvent mixture thatcoordinates and solvates lithium ions 4. In addition, the electrolyte 3may comprise a lithium-containing conductive salt (conductive lithiumsalt), for example lithium hexafluorophosphate (LiPF₆). As electrolytesolvent, the electrolyte 3 may especially comprise at least one(oligo)ether of the general chemical formula (1) and/or a (mono)ether ofthe general chemical formula (2). Optionally, the electrolyte 3 mayadditionally comprise at least one cyclic carbonate, for exampleethylene carbonate (EC), and/or at least one acyclic carbonate.

FIG. 1 illustrates that, during the charging operation, lithium ions 4(Li⁺) leave the cathode 2 (Li_((1-x))MO₂, Li_((1-x))M_(y)O_(z)) aresolvated by the electrolyte 3. The lithium ions 4 solvated in theelectrolyte 3 then migrate through the porous separator 7 to the anode1, where they intercalate into the graphite (Li_(x)C₆). At the sametime, electrons e⁻ move from the cathode output conductor 6 to the anodeoutput conductor, i.e. electrical current flows—through the outputconductors 5, 6 and the ampere meter 8—from the anode 1 to the cathode2.

FIG. 2 illustrates that, during the discharging operation, this processruns in reverse, with movement of electrons e⁻ from the anode outputconductor 5 to the cathode output conductor 6, i.e. flow of electricalcurrent—through the output conductors 5, 6 and the ampere meter 8—fromthe cathode 2 to the anode 1, and with deintercalation of the lithiumions 4 (Li⁺) out of the graphite (Li_(x)C₆) and solvation by theelectrolyte 3 and then migration, solvated in the electrolyte 3, throughthe porous separator 7 to the cathode 2 (Li_((1-x))MO₂,Li_((1-x))M_(y)O_(z)) and intercalation into the material thereof.

The charging and discharging operation can be expressed by the followingequation:

C₆+LiMO₂⇄Li_(x)C₆+Li_((1-x))MO₂.

1. An electrolyte, comprising at least one cyclic carbonate; and/or at least one acyclic carbonate; and at least one ether.
 2. The electrolyte as claimed in claim 1, wherein the electrolyte, based on a total weight of the carbonates and ethers, comprises ≧0.1% by weight to ≦20% by weight of ethers.
 3. The electrolyte as claimed in claim 1, wherein the electrolyte, based on a total weight of the carbonates and ethers, comprises: ≧50% by weight to ≦80% by weight of acyclic carbonates; ≧15% by weight to ≦40% by weight of cyclic carbonates and ≧0.1% by weight to ≦20% by weight of ethers.
 4. The electrolyte as claimed in claim 1, wherein the electrolyte, based on a total weight of the carbonates and ethers, comprises ≧0.5% by weight to ≦2% by weight of ethers.
 5. The electrolyte as claimed in claim 1, wherein the electrolyte further comprises at least one conductive lithium salt.
 6. The electrolyte as claimed in claim 1, wherein the at least one ether comprises an ether, comprising at least one of at least one carboxylic acid group, carboxylic ester group, hydroxyl group, thiol group, halogen atom, and sterically demanding group.
 7. The electrolyte as claimed in claim 1, wherein the at least one ether comprises an ether of the general chemical formula: R₁₁R₁₂R₁₃C—(CR₁₄R₁₅)_(x1)—[O—(CR₃₁R₃₂)_(a)—(CR₃₃R₃₄)_(b)]_(c)—O—(CR₂₄R₂₅)_(x2)—CR₂₁R₂₂R₂₃ and/or an ether of the general chemical formula: R₄₁R₄₂R₄₃C—(CR₄₄R₄₅)_(y1)—O—(CR₅₄R₅₅)_(y2)—CR₅₁R₅₂R₅₃ where 1≦c≦10, 1≦a≦5, 0≦b≦5 and x₁, x₂, y₁ and y₂ are each independently a number ≧0 and ≦5, where R₁₁ or R₄₁ is a carboxylic acid group or a carboxylic ester group or a hydroxyl group or a thiol group or a halogen atom or a branched or cyclic alkyl group or an alkenyl group or an alkoxy group or an aryl group or a heteroaryl group or an aryloxy group or a heteroaryloxy group, and R₁₂ and R₁₃ are each independently hydrogen or a carboxylic acid group or a carboxylic ester group or a halogen atom or an alkyl group or an alkenyl group or an alkoxy group or an aryl group or a heteroaryl group or an aryloxy group or a heteroaryloxy group or —CR₁₁R₁₂R₁₃ or —CR₄₁R₄₂R₄₃ is a branched alkyl group or a cyclic alkyl group or an alkenyl group or an aryl group or a heteroaryl group, where R₂₁, R₂₂, R₂₃ or R₅₁, R₅₂, R₅₃ are each independently hydrogen or a carboxylic acid group or a carboxylic ester group or a halogen atom or an alkyl group or an alkenyl group or an alkoxy group or an aryl group or a heteroaryl group or an aryloxy group or a heteroaryloxy group or —CR₂₁R₂₂R₂₃ or —CR₅₁R₅₂R₅₃ is a branched alkyl group or a cyclic alkyl group or an alkenyl group or an aryl group or a heteroaryl group, where R₁₄, R₁₅, R₃₁, R₃₂, R₃₃, R₃₄, R₂₄, R₂₅, R₄₄, R₄₅, R₅₄ and R₅₅ are each independently hydrogen or a carboxylic acid group or a carboxylic ester group or a halogen atom or an alkyl group or an alkenyl group or an alkoxy group or an aryl group or a heteroaryl group or an aryloxy group or a heteroaryloxy group.
 8. The electrolyte as claimed in claim 7, where R₃₁ and/or R₃₃ and/or R₁₂ and/or R₁₄ and/or R₂₂ and/or R₂₄ or R₄₂ and/or R₄₄ and/or R₅₂ and/or R₅₄ are an alkyl group and where R₃₂ and/or R₃₄ and/or R₁₃ and/or R₁₅ and/or R₂₃ and/or R₂₅ or R₄₃ and/or R₄₅ and/or R₅₃ and/or R₅₅ are hydrogen or an alkyl group.
 9. An electrolyte solvent or electrolyte additive for a lithium cell, of the general chemical formula: R₁₁R₁₂R₁₃C—(CR₁₄R₁₅)_(x1)—[O—(CR₃₁R₃₂)_(a)—(CR₃₃R₃₄)_(b)]_(c)—O—(CR₂₄R₂₅)_(x2)—CR₂₁R₂₂R₂₃ where 1≦c≦10, 1≦a≦5, 0≦b≦5 and x₁ and x₂ are each independently a number >0 and ≦5, where R₁₁ is a carboxylic acid group or a carboxylic ester group or a hydroxyl group or a thiol group or a halogen atom or a branched or cyclic alkyl group or an alkenyl group, especially a substituted or cyclic alkenyl group, or an alkoxy group, especially a branched or cyclic alkoxy group, or an aryl group or a heteroaryl group or an aryloxy group or a heteroaryloxy group, and R₁₂ and R₁₃ are each independently hydrogen or a carboxylic acid group or a carboxylic ester group or a halogen atom or an alkyl group or an alkenyl group or an alkoxy group or an aryl group or a heteroaryl group or an aryloxy group or a heteroaryloxy group or —CR₁₁R₁₂R₁₃ is a branched alkyl group or a cyclic alkyl group or an alkenyl group, especially a substituted or cyclic alkenyl group, or an aryl group or a heteroaryl group, and where R₂₁, R₂₂, R₂₃ are each independently hydrogen or a carboxylic acid group or a carboxylic ester group or a halogen atom or an alkyl group or an alkenyl group or an alkoxy group or an aryl group or a heteroaryl group or an aryloxy group or a heteroaryloxy group or —CR₂₁R₂₂R₂₃ is a branched alkyl group or a cyclic alkyl group or an alkenyl group, especially a substituted or cyclic alkenyl group, or an aryl group or a heteroaryl group, where R₁₄, R₁₅, R₃₁, R₃₂, R₃₃, R₃₄, R₂₄, R₂₅ are each independently hydrogen or a carboxylic acid group or a carboxylic ester group or a halogen atom or an alkyl group or an alkenyl group or an alkoxy group or an aryl group or a heteroaryl group or an aryloxy group or a heteroaryloxy group.
 10. The electrolyte solvent or electrolyte additive as claimed in claim 9, where R₁₁ is —CO₂H, —CO₂CH₃, —CO₂C₂H₅, —SH or —OH or —CR₁₁R₁₂R₁₃ is —CH(CH₃)₂, —CH₂—CH(CH₃)₂, —CH(CH₃)(C₂H₅), —C(CH₃)₃, —C₆H₁₁, —C₆F₁₁, —C₆H₅ or —C₆F₅, especially where R₂₁ is the same as R₁₁ or where —CR₂₁R₂₂R₂₃ is the same as —CR₁₁R₁₂R₁₃.
 11. The electrolyte solvent or electrolyte additive as claimed in claim 9, where R₃₁ and/or R₃₃ and/or R₁₂ and/or R₁₄ and/or R₂₂ and/or R₂₄ are an alkyl group and where R₃₂ and/or R₃₄ and/or R₁₃ and/or R₁₅ and/or R₂₃ and/or R₂₅ are hydrogen or an alkyl group.
 12. An electrolyte solvent or electrolyte additive for a lithium cell, of the general chemical formula: R₄₁R₄₂R₄₃C—(CR₄₄R₄₅)_(y1)—O—(CR₅₄R₅₅)_(y2)—CR₅₁R₅₂R₅₃ where y₁ and y₂ are each independently a number ≧0 and ≦5, where R₄₁ is a carboxylic acid group or a carboxylic ester group or a hydroxyl group or a thiol group or a halogen atom or a cyclic alkyl group or an alkenyl group, especially a substituted or cyclic alkenyl group, or an alkoxy group, especially a branched or cyclic alkoxy group, or an aryl group or a heteroaryl group or an aryloxy group or a heteroaryloxy group, and R₄₂ and R₄₃ are each independently hydrogen or a carboxylic acid group or a carboxylic ester group or a halogen atom or an alkyl group or an alkenyl group or an alkoxy group or an aryl group or a heteroaryl group or an aryloxy group or a heteroaryloxy group or —CR₄₁R₄₂R₄₃ is a cyclic alkyl group or an alkenyl group, especially a substituted or cyclic alkenyl group, or an aryl group or a heteroaryl group, where R₅₁, R₅₂, R₅₃ are each independently hydrogen or a carboxylic acid group or a carboxylic ester group or a halogen atom or an alkyl group or an alkenyl group or an alkoxy group or an aryl group or a heteroaryl group or an aryloxy group or a heteroaryloxy group or —CR₅₁R₅₂R₅₃ is a branched alkyl group or a cyclic alkyl group or an alkenyl group, especially a substituted or cyclic alkenyl group, or an aryl group or a heteroaryl group, where R₄₄, R₄₅, R₅₄ and R₅₅ are each independently hydrogen or a carboxylic acid group or a carboxylic ester group or a halogen atom or an alkyl group or an alkenyl group or an alkoxy group or an aryl group or a heteroaryl group or an aryloxy group or a heteroaryloxy group.
 13. The electrolyte solvent or electrolyte additive as claimed in claim 12, where R₄₁ is —CO₂H, —CO₂CH₃, —CO₂C₂H₅, —SH or —OH or —CR₄₁R₄₂R₄₃ is —C₆H₁₁, —C₆F₁₁, —C₆H₅ or —C₆F₅, especially where R₄₁ is the same as R₅₁ or where —CR₄₁R₄₂R₄₃ is the same as —CR₅₁R₅₂R₅₃.
 14. The electrolyte solvent or electrolyte additive as claimed in claim 12, where R₄₂ and/or R₄₄ and/or R₅₂ and/or R₅₄ are an alkyl group and where R₄₃ and/or R₄₅ and/or R₅₃ and/or R₅₅ are hydrogen or an alkyl group.
 15. A lithium cell or lithium battery comprising at least one of an electrolyte as claimed in claim 1, and/or an electrolyte solvent as claimed in claim 9, and an electrolyte additive as claimed in claim
 9. 16. The electrolyte as claimed in claim 5, wherein the at least one conductive lithium salt is lithium hexafluorophosphate.
 17. The electrolyte as claimed in claim 6, wherein the at least one ether comprises at least one of a monoether and an oligoether. 